Spring counterbalance



April 1953 E. M. TRAMMELL, SR., ET AL 2,635,282

SPRING COUNTERBALANCE Filed Oct. 2, 1950 INVENTORS. FIG. 3. EARL M. TRAMMELL SR.

EARL M. TRAMMELL JR:

Patented Apr. 21, 1953 SPRING COUNTERBALANCE Earl M. Trammell, Sr., and Earl M. Trammell, Jr., St. Louis, Mo.

Application October 2, 1950, Serial No. 188,036

6 Claims. (01. 16-197) This invention relates to improvements in spring elements for balances, and more particularly to a spring counterbalance assembly for sliding window sash.

Currently available balancing means for sliding window sash employ coil springs, usually a single such spring, suitably enclosed, being located adjacent the sashway structure, and the spring attached as by a flat metal tape, to a point of operative connection with the sash. Prevalent spring units for this purpose require an inordinate space externally of the head jamb or the frame structure, often entailing considerable labor for the removal of masonry, plaster, or other wall materials in order to provide a pocket adequate to accommodate the spring housing. Other recognized shortcomings of prevalent spring counterbalances, include a substantial variation in spring loading between open and closed positions of the sash served by the spring. Still other prevalent difiiculties with spring counterbalances now available to the trade, include a likelihood of breakage of either or both the spring and the connecting tape. It is accordingly a principal and general objective of the present developments to obviate, or at least to minimize the shortcomings noted.

There have heretofore been produced for certain other special fields of usage, coil springs of a flat or nearly flat metal stock characterized by registering convolutions, and by an almost uniform pull whether the spring coil be nearly fully wound, or nearly completely unwound. Springs of this type are sometimes referred to as compensating springs. However, the extended lengths of springs of this type exhibit a tendency to assume a bowedaspect, and under other conditions exhibit a tendency to twist, i. e., to curl about the longitudinal axis of the extended spring strip. These factors have rendered compensating types of spring not too well suited for use in counterbalancing window sash. Accordingly, a further and important object of the present invention is realized in a spring assembly such as will enable the use of compensating-load springs in a manner to maintain in substantially planar relation, that length of the spring or springs extended into the sashway.

A further objective improvement, reflected in a lower assembly cost and minimum service requirements, lies in the use of a plurality, usually a pair, of compensating springs, in adjacence but in relatively reversed mutual relation.

A u e ad an g ea i e in an advanced embodiment of the present invention, consists of improved provisions which may be integral with the spring elements per se, for maintaining adjacent lengths of the compensating spring strip in mutual registry. This phase of the improvements applies both to the extended spring lengths, as Well as to the adjacent convolutions thereof.

The foregoing and numerous other objectives and advantages will more clearly appear from the following detailed description of a currently preferred embodiment of the invention, particularly when considered in connection with the accompanying drawing, in which:

Fig. 1 is a vertical sectional elevation, the sectional portions of which are taken lengthwise through a horizontally disposed spring housing, located in the upper left hand portion of a sliding window sash assembly, and showing one manner of connection of thecounterbalance spring means to the sash;

Fig. 2 is an 'elevational view in perspective, of a balance spring unit embodying the present improvements, as same would appear out of assembly with the window frame structure, the extended spring ends or tapes being partly broken away for clarity of certain features, and

Fig. 3 is a transverse sectional view of the connecting spring ends or tapes, particularly as viewed along line 33 of Fig. 2.

Referring now bycharacters of reference to the drawing, and first to Fig. 1, there is indicated at SR an upper portion of a sash nail, the sash for brevity of present description being con-' sidered as conventional, and provided with a vertical rout or groove R, secured to the inner face of which is one element [0 of a detachable tape or spring connector, attached as by screws l I.

It will be understood that the sash may be slidably guided by and between the adjacent pulley stiles, beads and other fixed elements, herein referred to collectively as constituting the sashay. A fragmentary part of the pulley stile is indicated at PS, and horizontally at the top of the Window frame structure is a head jamb I-IJ, which is or may be regarded as conventional.

For mounting of the spring counterbalance assembly, the head jamb is provided with a recsuitably attached, as by welding, to a base or mounting plate [3.

This base element is of greater area than the opening RR; so as to provide a bottom closure for the opening RR as well as a support for the spring housing and contents. Plate I3 is provided with one or a plurality of screw openings i l to receive a mounting screw or, screws i5 engaging the head jamb.

The casing [2, with advantageous distinction over prevalent spring balance assemblies, is of a horizontally elongate proportion. This design considerably minimizes the amount of wall material sometimes needed to be removed above the head jamb, in orderto accommodate the spring assembly. As will appear from Fig. l, the height of the member l2 above the jamb need be of no. more than the usual thickness of the latter.

This factor is of cost importance, particularly in case a brick wall or one of concrete, tile'and other ceramic materials must be drilled or cut.

away to accommodate the spring. assembly.

As will best appear from Fig. 1, plate I3 is provided with a pair of spaced, vertical, internal flanges l6 and H, the spacing of which is such as to form therebetween a. rectangular guide. pas.- sage for the paired; tapes, later described, issuing through such passage intov the sashway.

Within the casing. I2I3 are located a pair of coil springs 20 and 22, each of which is formed of a single length of a substantial flat metal stock of suitable temper. It will be noted. from Fig. 1 that the arrangement of these springs (which may in structure be identical.) is such that. if viewed from a given side. of the casing, the two are relatively reversed.

Thus the spring 20 may be. considered in. Fig. 1 as a clockwise spring, while the companion spring 22 may be considered counterclockwise. Both springs are mounted in floating relation within housing l2-I3, i'. e. no part of either spring is anchored orattached to a pivot pin, arbor or winding drum, the spring action and loading being in the present embodiment derived entirely from the tendency of the springs to recoil When the convolutions are extended. It should be understood, however, that it is expressly within the intendment of the present developments to: utilize, under certain special conditions, a pair of conventional springs in a relatively reversed juxtaposed relation.

The inside spacing of the two sides of the casing l2, indicated at 2'3 and 24, conforms somewhat closely to the width of the springs, yet with sufficient working clearance between the sides of the coils and the inside faces of the sides of member I2. Thus, as the spring ends are retracted, or as they issue from the enclosure, those portions of the springs within the housing are guided to registering relation, and are. substantially in the same plane at all times.

It is a further preference, substantially as shown in Fig. 1, to form the upper end portions of member I2 of arcuate contour as indicated at 25, these portions being curved on radii substantially the same as the normal radius of each wound spring. 'From this it will appear that each of the springs 20 and 22 is substantially positioned solely by external guidance, so that it operates about a substantially fixed center. This effect is derived by the rounded portions 25 and flanges l6 and IT, as well as other parts of the casing.

It is, of course, possible to realize certain of the advantages of the present counterbalance spring assembly by attaching tothe ends of the springs proper, a pair of metal tapes (not shown) Such tapes would be utilized in the same relation, and kept in registry as are the en e ements of the springs 20 and 22. r

For brevity of present disclosure the extended end portions 3!! and 3|, while serving as metal connecting tapes, are shown as integral extensions of the spring strip stock, and sofunction in those lengths which are withdrawn from the casing l2--I3.

It is a preference to attach together in an outer end region, the tape or spring elements 3-0-3 I, as by one or more rivets 32. As shown, the members 32 also serve to. attach to both of the tapes a hook-shaped connector element 33, the hook end 34 of which engages a corresponding relatively inverted hook of the connector element IO. Thus the parts l0 and 33, each of about thewidthof. the tapes or spring ends 30--3I,

coast to provide a quick-detachable connection between the springs and the sash member SR. This feature'is of particular advantage in a removable sash assembly so as to permit retention and anchorage of the spring or tape ends in a position readily to re-engage the. removed sash, upon re-appl'ication thereof to the sashway;

The springs 23 and 22 are shown, but without restriction, as of compensating-load type, so as to exhibit a nearly uniform sash-lifting efiort, whether the sashbe raised or lowered. Springs of this type which are available to the trade for other purposes, are usually of a concave-convex strip section, and are wound with the convex side toward the outside of the coil. Thus, as the paired strips are withdrawn, they will issue in a back-to-back. or face-to-face relation as shown by Fig. 3. In utilizing a single spring of this type, mounted for assembly as is spring 20, the issuing end of the strip will tend markedly to bow inwardly toward the center of the sash or sashway. Such unsightly and undesirable deformation results in interference with the moving parts, particularly in window units of certain special construction. Likewise, springs of thistype frequently, when used singly, exhibit a tendency to twist about the longitudinal axis of the strip. Both of the noted deforming tendencies are fully overcome by utilizing the paired springs with extended ends in registering, contiguous relation, as shown. The bowing tendency of each spring is in an opposite direction to that of the other, and any twisting tendency of either is directly compensated for by the opposite efiect of its companion. Thus the paired springs, possessing all advantages of spring elements of compensating load type, will nevertheless operate at all times in a vertical plane and without distortion.

A further improvement tending to maintain the registering relation of the extended lengths of spring or strip, appears in Fig. 2. The mating faces of the springs 303I are each provided for this purpose with a plurality of slightly spaced, parallel, longitudinal, score lines, this formation being indicated at 40 (Fig. 2). These patterns of lengthwise indentation act to prevent lateral slippage of either tape away from the other. The registry of the spring or tape ends 30 or 3! is further promoted by the guiding-effect of the opposite ends of the rectangular port and passage 4!, Fig. 2, which results from the spacing of flanges I6 and i! above described.

It is perhaps a more prevalent practice to locate a spring counterbalance in and above the head jamb, as shown and described herein. However, in certain installations, these units may be mounted in one of the vertical stiles, with equal advantages.

The operation of the device is thought to have become fully apparent from the foregoing description of the elements of a preferred embodiment, but it may be noted for completeness, that the characteristics of the paired springs 20 and 22 are such that they will closely counterbalance the associated sash. Now obviously, as the sash is lowered, the strip ends 30-3l will be extended. pro tanto, and the successive turns of both springs 20 and 22 will be unwound, there being a certain frictional resistance between adjacent unwound turns of each spring, due to the tendency of these turns to coil and constrict themselves. As the sash is again raised, the opposite action will take place, and as the extended ends 393| are retracted into the housing, the springs again assume about the proportion and relation of the convolutions, as shown by Fig. 1.

It will, of course, now be obvious that the provision of the springs in pairs connected to the sash at a common point, provides a desirable reserve in that, if either spring should break or become disconnected for any reason, the remaining spring will still provide a partial balancing load on the sash.

Although the improvements have been described by detailed reference to a single preferred embodiment, the detail of description should be understood in an instructive, rather than in any limiting sense, numerous variants being possible within the fair scope of the claims hereunto appended.

We claim as our invention:

1. In a counterbalance assembly for a sliding window sash, a pair of springs of convolute character, a housing of horizontal elongate character for the springs adapted for mounting close to a sashway serving the window sash, the housin being so formed as to enclose both springs in a substantially co-planar relation, said springs being disposed in relatively reversed positions, the springs including unwound portions which are withdrawable from the housing into the sashway in registering adjacence, detachable connecting means common to the springs for engagement thereof with the sash, the springs being secured together in the region of said sash connection, said springs being of compensating-load type so as to exert a substantially uniform force to the sash at all times, the unwound portions of said springs being operable in a straight planar relation so as to constitute a straight connecting tape.

2. In a counterbalance for sliding window sash, a pair of adjacent coil springs, a horizontally elongate spring housing adapted for fixed location adjacent the sashway, the springs being disposed in relatively reversed positions in said housing, and being connected together at their leading ends, each spring being disposed in floating relation in said housing, a common connector serving the springs for detachable securement thereof to a sliding sash, the springs being so arranged in the housing as to be withdrawable therefrom into the sashway, with the withdrawn lengths of the springs substantially contiguous relation, said springs being of compensating-load type so as to exert a nearly uniform sash-lifting effort to said sash in any position the withdrawn lengths of the springs being operable in a vertical plane, and serving as a straight tape in the sashway.

3. H1 a spring counterbalance for sliding sash, a horizontally elongate spring housing for location adjacent the path of movement of the sash, a pair of springs of a closely wound convolute character, and each of a concave-convex cross-section, the springs being disposed in floating relaportions of said springs being operable in a substantially vertical plane, whereby to serve as a straight tape. i

4. A spring counterbalance assembly adapted for sliding window sash, and consisting of a pair of coil springs disposed in relatively reversed positions, a horizontally elongate housing for the springs, for location adjacent asashway serving the sash, and from which housing the unwound portions of the springs may be withdrawn in contiguous relation, the said springs being of a slightly curved cross-section, each of said springs including a free end portion, such end portions being attached to each other in back-to-back relation, and a connection serving both said spring ends, for attachment thereof to the sash, the springs being of compensating-load type so as to exert a nearly uniform pull to the sash at all times, the unwound portions of said springs being operable in a substantially vertical plane.

5. In a spring counterbalance assembly adapted for use in connection with a sliding window sash and structure forming a sashway therefor, a spring housing including a mounting plate arranged for disposition close to the plane of the lower surface of the head jamb, the housing being of a horizontally elongate character, and of substantially lesser height than length; a pair of closely wound convolute metal springs disposed in the housing and floatingly arranged therein, the springs being of a compensating-load type, said mounting plate being provided with a spring port in the lower portion of the spring housing, through which port the free ends of the springs may issue into the sashway, a pair of spaced guide flanges projected upwardly of said plate and into the housing, the paired springs being relatively oppositely disposed in respect to the housing, the springs each being formed of a strip stock of tempered character and each of a concavo-convex cross-section, the arrangement of springs being such that the unwound portions thereof issuing through said port, are adapted to enter the sashway in back-to-back relation, and are adapted to operate in a vertical plane in said sashway; and a connector for attachment of the springs to the sash served thereby, the compensating springs cooperating to exhibit a nearly uniform sash-lifting effort in any position of said sash.

6. In a spring counterbalance assembly adapted for use in connection with a sliding window sash and structure forming a sashway therefor, a spring housing adapted for attachment to the head jarnb of the sliding sash assembly, and including a mounting plate apertured for mounting screws, said plate being arranged for disposition close to the plane of the lower surface of the head jamb, the housing being of a horizontally elongate character, and of substantially lesser height than length; a pair of closely wound convolute metal springs of compensating-load type disposed in the housing and floatingly arranged therein so as to be free for winding and unwinding actuation devoid of restraint by any part of the housing, said mounting plate being provided with a spring port substantially midway of the length and in the lower portion of the spring housing,

throughwhich portthe free ends of the springs may issue into the sashway, a pair of, spaced guide flanges projected upwardly of said plate and into the housing between said springs, the paired springs being relatively oppositely disposed in respect to the housing in such manner that one spring is of clockwise character and the other said spring counterclockwise, the springs each being Iormedof a strip stock of tempered character and each of a concave-convex cross-section, the arrangement of springs being such that the unwound portions thereof issuing through said port, are adapted to enter the sashway in close parallel adjacence, in mutual register, and in back-toback relation; the free ends of the springs being secured together, and a connector for attachment of the springs to the sash served thereby.

EARL M. TRAMMELL, SR.

EARL M. TRAMMELL, JR.

Number Name Date 5 151,881 Jefirey June 9, 1874 198,179 Anderson Dec. 18, 1877 213,901 Horton July 5, 1881- 1,226,843 Arvine May 22, 1917 1,373,955 Erickson Apr. 5, 1921 10 1,699,267 A-ppleby Jan. 15, 1929;

OTHER REFERENCES The Ironmonger, page 139, October 27, 1888.,

& Referencesclted in the file of this patent H UNITED STATES PATENTS 

